dump: add 'query-dump-guest-memory-capability' command

'query-dump-guest-memory-capability' is used to query the available formats for
'dump-guest-memory'. The output of the command will be like:

-> { "execute": "query-dump-guest-memory-capability" }
<- { "return": { "formats":
                    ["elf", "kdump-zlib", "kdump-lzo", "kdump-snappy"] }

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

dump.c

@@ -1791,3 +1791,36 @@ void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
 
     g_free(s);
 }
+
+DumpGuestMemoryCapability *qmp_query_dump_guest_memory_capability(Error **errp)
+{
+    DumpGuestMemoryFormatList *item;
+    DumpGuestMemoryCapability *cap =
+                                  g_malloc0(sizeof(DumpGuestMemoryCapability));
+
+    /* elf is always available */
+    item = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    cap->formats = item;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_ELF;
+
+    /* kdump-zlib is always available */
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB;
+
+    /* add new item if kdump-lzo is available */
+#ifdef CONFIG_LZO
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO;
+#endif
+
+    /* add new item if kdump-snappy is available */
+#ifdef CONFIG_SNAPPY
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY;
+#endif
+
+    return cap;
+}

qapi-schema.json

@@ -2861,6 +2861,30 @@
   'data': { 'paging': 'bool', 'protocol': 'str', '*begin': 'int',
             '*length': 'int', '*format': 'DumpGuestMemoryFormat' } }
 
+##
+# @DumpGuestMemoryCapability:
+#
+# A list of the available formats for dump-guest-memory
+#
+# Since: 2.0
+##
+{ 'type': 'DumpGuestMemoryCapability',
+  'data': {
+      'formats': ['DumpGuestMemoryFormat'] } }
+
+##
+# @query-dump-guest-memory-capability:
+#
+# Returns the available formats for dump-guest-memory
+#
+# Returns:  A @DumpGuestMemoryCapability object listing available formats for
+#           dump-guest-memory
+#
+# Since: 2.0
+##
+{ 'command': 'query-dump-guest-memory-capability',
+  'returns': 'DumpGuestMemoryCapability' }
+
 ##
 # @netdev_add:
 #

qmp-commands.hx

@@ -826,6 +826,26 @@ Notes:
 
 (1) All boolean arguments default to false
 
+EQMP
+
+    {
+        .name       = "query-dump-guest-memory-capability",
+        .args_type  = "",
+    .mhandler.cmd_new = qmp_marshal_input_query_dump_guest_memory_capability,
+    },
+
+SQMP
+query-dump-guest-memory-capability
+----------
+
+Show available formats for 'dump-guest-memory'
+
+Example:
+
+-> { "execute": "query-dump-guest-memory-capability" }
+<- { "return": { "formats":
+                    ["elf", "kdump-zlib", "kdump-lzo", "kdump-snappy"] }
+
 EQMP
 
     {